When a computer is turned on, a boot loader such as a basic input-output system (BIOS) that is stored in non-volatile solid state memory of the computer is invoked to begin what is known as a “boot” process, in which various initialization chores are undertaken. Among the most important of these chores is the copying of an operating system from disk storage of the computer over into typically a volatile solid state memory of the computer, for execution of the operating system by the processor of the computer when the computer is being used. When the computer is turned off or when it is “re-booted”, the operating system is flushed from the memory. By executing the operating system from the relatively fast memory instead of from the disk, computer operations are accelerated.
An essential tool in booting is the Master Boot Record (MBR), which BIOS typically accesses early on in the boot process from secondary storage. In current implementations the MBR may be stored in the first 63 sectors of the hard disk drive, with a partition boot record (PBR) being stored in succeeding disk sectors. The MBR contains a record of disk locations of various O.S. data that BIOS must know to complete the boot, including a partition table, which contains the layout of data on the disk. The partition table may have space for, e.g., four partitions, with each entry including the partition size, marker if the partition is the boot partition, and type that defines the file system.
As recognized by the present invention, a malevolent virus might be designed to zero out the first 63 sectors of a disk or to otherwise destroy the MBR and thus prevent booting. As further recognized herein, while the MBR can be backed up to external storage, restoring it requires locating and loading the information from external storage, which can take time, and furthermore depending on how frequently the user remembers to back up the MBR, the externally-stored copy might be outdated. With these critical recognitions in mind, the invention herein is provided.